I've been quite keen on the new FFI too - apologies if this is old news, but have you tried the [0] jextract stuff for some of the boilerplate gubbins?

[0]: https://github.com/openjdk/jextract

No! Thanks for the callout! That would certainly help on my path. My main goal was to insulate calls to avoid overly complicated reference counting when integrating large native surfaces into as Java program, but certainly an important aspect is getting the function signatures to target in the first place. I threw something bad together to work sort of like this (testing using proton), but I'm more than happy to bin it for something that just-works.